Photo credit: NASA
The Sahara (Arabic: الصحراء الكبرى, aṣ-ṣaḥrā´, "The Great Desert") is the world's largest hot desert at over 9,000,000 square kilometres (3,500,000 sq mi). The Sahara defines the borders of North Africa and has an intermittent history that may go back as much as 2.5 million years.